The novel’s central conflict is largely driven by parents attempting to protect their biological and surrogate children, revealing how the depth of the parent-child bond can lead to individuals surmounting seemingly impossible challenges. The novel thus celebrates the power of parental love and protectiveness.

Sheena loves her children more than anything and is catapulted into a terrible dilemma when she receives the ransom note. She decides to follow the instructions and not alert the police because she wants to maximize any chance of saving her daughters. Sheena shows her intelligence, composure, and fortitude by carrying out the ransom tasks without any support, as she cannot confide in anyone. Her courage under pressure and ability to shoulder a heavy burden alone reflect her role as a single mother who is also the caregiver to her elderly father. She makes hard choices—such as moving her father into the elder care facility—driven by love and a desire to protect those she cares for.

While Sheena embodies parental love outside of the bunker, Jessa draws on the power of protectiveness inside of it. Even when Jessa is initially cold towards the children, she is shaped by the magnitude of her love for her biological daughter, calculating that anything that leads to rescue will increase her chances of seeing Sophie again. However, as time passes, Jessa’s nurturing and protective instincts come to the fore as she begins to see all of the students as surrogate children. Especially since she has been denied the ability to nurture her own child for years, she steps into an encouraging and caregiving role, helping Sage to keep her spirits up. Jessa shows care during their greatest hour of need, when the situation seems hopeless. Her protective and loving actions towards the children transform her own outlook, allowing her to finally let go of her past.

While the maternal love displayed by Sheena and Jessa is central to the plot, Sheena’s father reveals that parental love is displayed by both mothers and fathers and can extend across generations. He has been a loving caregiver to his granddaughters, and he intervenes at a pivotal moment to protect Sage’s physical safety. The intertwined storylines surrounding these characters reveal how different parents all work in distinct but ultimately interconnected ways to save the children.

Although Sage is not a parent, she also displays a version of this theme in her protectiveness and care towards Bonnie and the younger children. Anytime a character is motivated by a desire to protect the vulnerable, they are able to display courage and strength, which is shown to be more powerful than being motivated by greed.